mapbox-gl/js/render/set_pattern.js

A WebGL interactive maps library

'use strict';

var pixelsToTileUnits = require('../source/pixels_to_tile_units');

module.exports = setPattern;

function setPattern(image, tile, coord, painter, program, includeHeightFactor) {
    var gl = painter.gl;

    var imagePosA = painter.spriteAtlas.getPosition(image.from, true);
    var imagePosB = painter.spriteAtlas.getPosition(image.to, true);
    if (!imagePosA || !imagePosB) return;

    gl.uniform1i(program.u_image, 0);
    gl.uniform2fv(program.u_pattern_tl_a, imagePosA.tl);
    gl.uniform2fv(program.u_pattern_br_a, imagePosA.br);
    gl.uniform2fv(program.u_pattern_tl_b, imagePosB.tl);
    gl.uniform2fv(program.u_pattern_br_b, imagePosB.br);
    gl.uniform1f(program.u_mix, image.t);

    gl.uniform1f(program.u_tile_units_to_pixels, 1 / pixelsToTileUnits(tile, 1, painter.transform.tileZoom));
    gl.uniform2fv(program.u_pattern_size_a, imagePosA.size);
    gl.uniform2fv(program.u_pattern_size_b, imagePosB.size);
    gl.uniform1f(program.u_scale_a, image.fromScale);
    gl.uniform1f(program.u_scale_b, image.toScale);

    var tileSizeAtNearestZoom = tile.tileSize * Math.pow(2, painter.transform.tileZoom - tile.coord.z);

    var pixelX = tileSizeAtNearestZoom * (tile.coord.x + coord.w * Math.pow(2, tile.coord.z));
    var pixelY = tileSizeAtNearestZoom * tile.coord.y;
    // split the pixel coord into two pairs of 16 bit numbers. The glsl spec only guarantees 16 bits of precision.
    gl.uniform2f(program.u_pixel_coord_upper, pixelX >> 16, pixelY >> 16);
    gl.uniform2f(program.u_pixel_coord_lower, pixelX & 0xFFFF, pixelY & 0xFFFF);

    if (includeHeightFactor) {
        gl.uniform1f(program.u_height_factor, -Math.pow(2, painter.transform.tileZoom) / tileSizeAtNearestZoom >> 3);
    }

    gl.activeTexture(gl.TEXTURE0);
    painter.spriteAtlas.bind(gl, true);
}